Cause : Communication fault comes when no control data was received from the connected PLC when using serial communications.

Typically "EF0" fault occurs when a drive is communicating with a PLC via Modbus, BACnet MS/TP, Apogee, or Metasys and communication is lost for the duration of time set in parameter.

1. Baud rate and parity checksum is set incorrect- check communication parameters correct or not.
2. Communication interrupted for long time- check the interface wiring.